Animal lovers hit the roof after it was revealed that Republican presidential candidate Mitt Romney strapped his Irish setter to the top of his car during a 12-hour family drive from Boston to Ontario, terrifying the hapless dog and causing a health hazard to fellow road-users.

According to the Boston Globe, the former Massachusetts governor placed the dog, called Seamus, in a kennel attached to the roof of his white Chevy station wagon. He and his wife and five sons then set off on holiday.

After a few miles, Mr Romney's eldest son, Tagg, raised the alarm. "Dad!" he yelled. "Gross!" A brown liquid was dripping down the rear windscreen.

In protest at his treatment perhaps, Seamus had suffered a diarrhoea attack. The results made driving difficult.

Exhibiting presidential-style cool in a crisis, and with his family howling in disgust, Mr Romney pulled over. He borrowed a hosepipe and washed down Seamus, the car, and the kennel - then set off again with the dog still on the roof.

The Massachusetts Society for Prevention of Cruelty to Animals said the 1983 incident, which came to light this week, could be investigated for possible dog endangerment.

Ingrid Newkirk, an animal rights activist, said Mr Romney had placed the dog under "extreme stress", causing it to "lose control of its bowels". The incident verged on dog and child abuse, she suggested.

Mr Romney said the row was a fuss about nothing. Seamus enjoyed being on the roof, he said. "He scrambled up there every time we went on trips."